coöperation. The pandas rapidly became
healthier, and, among other things,
began having more sex.
When I visited the National Zoo's
pandas, this spring, Mei Xiang
had recently been artificially inseminated,
following the pair's latest unsuccessful at-
tempt at natural breeding. To obtain the
semen, veterinarians had inserted a low-
voltage probe into Tian Tian's rectum,
positioned it near his prostate, and pulsed
the current. Suzan Murray, the chief vet-
erinary medical officer, gave me a tour of
the facility in which the procedure had
taken place. In one operating room, I saw
an examination table mounted on a hy-
draulic lift. Murray said that the zoo's vets
had used it for a zebra whose intestine had
become twisted---an operation that in-
volved opening the animal's abdomen and
untangling the intestine as though it were
a garden hose. On the far wall was a cal-
endar, drawn on a whiteboard with col-
ored markers: I saw that an oryx and a
macaque were going to have vasectomies
the following week, and that Tian Tian
had been scheduled for another electro-
ejaculation. The new ejaculate would be
frozen, and stored in liquid nitrogen in
one of several dozen freezers the zoo uses
for such purposes. Freezing semen was
first done in the cattle industry, in the
nineteen-fifties, and the technique was
later applied to other animals, including
humans. The zoo's collection includes
samples from many endangered species,
but not all. Scientists still don't know how
to properly freeze elephant semen.
A little later, Brandie Smith, the
panda curator, took me into a non-
public area in back of the panda enclo-
sure. We stood behind a painted yellow
line, which marked the distance an adult
panda can reach with a paw, and watched
while Tian Tian came up to the fence to
receive various treats. Pandas resemble
enormous plush toys---a key element of
their appeal to humans---but their eyes
are broadly expressive, in the way that
dogs' eyes are. Pandas also have a prom-
inent bone in their forepaws which func-
tions almost like a human thumb. As a
consequence, they are able to hold things
almost as we do, making them seem less
like real bears and more like Disney an-
imations. Tian Tian, as he moved from
treat to treat along the edge of his enclo-
sure, had a heavy ursine gait, but when
he stood and gripped the fence he be-
came a storybook character.
I met Mei Xiang a little later, in a
different area. She rapidly made her way
down a tunnel-like cage, called a training
chute, and when she got to the end---
where I was standing with Smith and
several keepers, behind another yellow
line---she sat, extended her left foreleg
through a small opening, onto a metal
tray, and, using her opposable pseudo-
thumb, gripped a bar at the end of the
tray. The tray is used for drawing blood,
and gripping the bar prevents a panda
from accidentally clawing a human. This
time, the veterinarians didn't need blood,
but Marty Dearie, one of the keepers,
used a finger to prod the inside of her
elbow anyway, to keep her in practice,
and then rewarded her with a squirt of
something sweet from a squeeze bottle.
At one time, blood draws and other
routine veterinary procedures could be
done only under general anesthesia, but
Mei Xiang and Tian Tian have both been
trained to open their mouth for an oral ex-
amination, offer a shoulder for an injec-
tion, and hold their forepaws above their
head, airport-security style, for a chest
X-ray. Handling zoo animals this way
began in the nineteen-eighties, using "op-
erant conditioning" techniques borrowed
from performing-animal handlers. Since
then, polar bears have been taught to par-
ticipate in hearing studies; elephants have
learned to extend a foot through the bars
of their enclosure and keep it elevated for
a podiatric examination; great apes that
need to be knocked out for a complex
medical procedure have been taught to
allow a keeper to inject them with an an-
esthetic and then, if the initial dose proves
insufficient, to come back for a second. A
properly trained lion, responding to hand
signals and spoken commands, will hold
its mouth open for a dental exam and lean
against its cage to receive a vaccination.
"With great apes," Dearie said, "you
just show them what you want and they're,
like, Oh, O.K., I'll figure that out---be-
cause their minds work more like ours.
Pandas think differently." Trainers teach
pandas new behaviors not by demon-
strating them but by using treats to re-
ward movements that are serendipitously
similar to the ones they're looking for.
Then they gradually incorporate addi-
tional elements, as though they were as-
sembling a puzzle. Nothing is done coer-
cively. Mei Xiang had entered the training
chute voluntarily, and she was free to leave.
Elementary-school teachers, among
"I want to spill the beans, but I'm waiting till I have
access to classified or sensitive beans."